«ComboBox» con una entrada

Un ComboBox puede contener un widget Entry para la entrada de texto arbitrario, mediante la especificación de true al parámetro has_entry del constructor.

11.6.1. La columna de texto

So that the Entry can interact with the drop-down list of choices, you must specify which of your model columns is the text column, with set_entry_text_column(). For instance:

m_combo.set_entry_text_column(m_columns.m_col_name);

Cuando seleccione una opción de la lista desplegable, el valor de esta columna se pondrá en el widget Entry.

11.6.2. La entrada

Dado que el usuario puede introducir texto arbitrario, una fila del modelo activa es suficiente para indicar qué texto ha introducido el usuario. Por lo tanto, debe obtener el widget Entry con el método ComboBoxEntry::get_entry() y llamar a get_text() sobre él.

11.6.3. Responder a los cambios

When the user enters arbitrary text, it may not be enough to connect to the changed signal, which is emitted for every typed character. It is not emitted when the user presses the Enter key. Pressing the Enter key or moving the keyboard focus to another widget may signal that the user has finished entering text. To be notified of these events, connect to the Entry's activate and focus_out_event signals, like so

auto entry = m_Combo.get_entry();
if (entry)
{
  // Alternatively you can connect to m_Combo.signal_changed().
  entry->signal_changed().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_entry_changed) );

  entry->signal_activate().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_entry_activate) );

  entry->signal_focus_out_event().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_entry_focus_out_event) );
}
The changed signals of ComboBox and Entry are both emitted for every change. It doesn't matter which one you connect to. But only Entry's focus_out_event signal is useful here.

Los eventos de X se describen con mayor detalle en la sección Señales de eventos de X en el apéndice.

11.6.4. Ejemplo completo

Figura 11-3«ComboBox» con una entrada

Source Code

File: examplewindow.h (For use with gtkmm 4)

#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include <gtkmm/window.h>
#include <gtkmm/combobox.h>
#include <gtkmm/liststore.h>

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  virtual ~ExampleWindow();

protected:
  //Signal handlers:
  void on_combo_changed();
  void on_entry_changed();
  void on_entry_has_focus_changed();

  //Signal connection:
  sigc::connection m_ConnectionHasFocusChanged;
  bool m_entry_had_focus {false};

  //Tree model columns:
  class ModelColumns : public Gtk::TreeModel::ColumnRecord
  {
  public:

    ModelColumns()
    { add(m_col_id); add(m_col_name); }

    Gtk::TreeModelColumn<Glib::ustring> m_col_id; //The data to choose - this must be text.
    Gtk::TreeModelColumn<Glib::ustring> m_col_name;
  };

  ModelColumns m_Columns;

  //Child widgets:
  Gtk::ComboBox m_Combo;
  Glib::RefPtr<Gtk::ListStore> m_refTreeModel;
};

#endif //GTKMM_EXAMPLEWINDOW_H

File: main.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <gtkmm/application.h>

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create("org.gtkmm.example");

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app->run(window, argc, argv);
}

File: examplewindow.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <iostream>

ExampleWindow::ExampleWindow()
: m_Combo(true /* has_entry */)
{
  set_title("ComboBox example");

  //Create the Tree model:
  //m_refTreeModel = Gtk::TreeStore::create(m_Columns);
  m_refTreeModel = Gtk::ListStore::create(m_Columns);
  m_Combo.set_model(m_refTreeModel);

  //Fill the ComboBox's Tree Model:
  auto row = *(m_refTreeModel->append());
  row[m_Columns.m_col_id] = "1";
  row[m_Columns.m_col_name] = "Billy Bob";
  /*
  auto childrow = *(m_refTreeModel->append(row.children()));
  childrow[m_Columns.m_col_id] = 11;
  childrow[m_Columns.m_col_name] = "Billy Bob Junior";

  childrow = *(m_refTreeModel->append(row.children()));
  childrow[m_Columns.m_col_id] = 12;
  childrow[m_Columns.m_col_name] = "Sue Bob";
  */

  row = *(m_refTreeModel->append());
  row[m_Columns.m_col_id] = "2";
  row[m_Columns.m_col_name] = "Joey Jojo";

  row = *(m_refTreeModel->append());
  row[m_Columns.m_col_id] = "3";
  row[m_Columns.m_col_name] = "Rob McRoberts";

  /*
  childrow = *(m_refTreeModel->append(row.children()));
  childrow[m_Columns.m_col_id] = 31;
  childrow[m_Columns.m_col_name] = "Xavier McRoberts";
  */

  //Add the model columns to the Combo (which is a kind of view),
  //rendering them in the default way:
  //This is automatically rendered when we use set_entry_text_column().
  //m_Combo.pack_start(m_Columns.m_col_id, Gtk::PackOptions::EXPAND_WIDGET);
  m_Combo.pack_start(m_Columns.m_col_name);

  m_Combo.set_entry_text_column(m_Columns.m_col_id);
  m_Combo.set_active(1);

  //Add the ComboBox to the window.
  add(m_Combo);

  //Connect signal handlers:
  m_Combo.signal_changed().connect(sigc::mem_fun(*this, &ExampleWindow::on_combo_changed));

  auto entry = m_Combo.get_entry();
  if (entry)
  {
    entry->signal_changed().connect(sigc::mem_fun(*this,
      &ExampleWindow::on_entry_changed) );
    m_ConnectionHasFocusChanged = entry->property_has_focus().signal_changed().
      connect(sigc::mem_fun(*this, &ExampleWindow::on_entry_has_focus_changed));
  }
  else
    std::cout << "No Entry ???" << std::endl;
}

ExampleWindow::~ExampleWindow()
{
  // The has_focus changed signal may be emitted while m_Combo is being destructed.
  // The signal handler can generate critical messages, if it's called when
  // m_Combo has been partly destructed.
  m_ConnectionHasFocusChanged.disconnect();
}

void ExampleWindow::on_combo_changed()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    std::cout << "on_combo_changed(): Row=" << m_Combo.get_active_row_number()
      << ", ID=" << entry->get_text() << std::endl;
  }
}

void ExampleWindow::on_entry_changed()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    std::cout << "on_entry_changed(): Row=" << m_Combo.get_active_row_number()
      << ", ID=" << entry->get_text() << std::endl;
  }
}

void ExampleWindow::on_entry_has_focus_changed()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    const bool entry_has_focus = entry->has_focus();
    if (m_entry_had_focus && !entry_has_focus)
    {
      // entry->has_focus() has changed from true to false; entry has lost focus.
      std::cout << "on_entry_has_focus_changed() to not focused: Row="
        << m_Combo.get_active_row_number() << ", ID=" << entry->get_text() << std::endl;
    }
    m_entry_had_focus = entry_has_focus;
  }
}

11.6.5. Ejemplo de texto simple

Figura 11-4«ComboBoxText» con una entrada

Source Code

File: examplewindow.h (For use with gtkmm 4)

#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include <gtkmm/window.h>
#include <gtkmm/comboboxtext.h>

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  virtual ~ExampleWindow();

protected:
  //Signal handlers:
  void on_combo_changed();
  void on_entry_changed();
  void on_entry_has_focus_changed();

  //Signal connection:
  sigc::connection m_ConnectionHasFocusChanged;
  bool m_entry_had_focus {false};

  //Child widgets:
  Gtk::ComboBoxText m_Combo;
};

#endif //GTKMM_EXAMPLEWINDOW_H

File: main.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <gtkmm/application.h>

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create("org.gtkmm.example");

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app->run(window, argc, argv);
}

File: examplewindow.cc (For use with gtkmm 4)

#include "examplewindow.h"
#include <iostream>

ExampleWindow::ExampleWindow()
: m_Combo(true /* has_entry */)
{
  set_title("ComboBoxText example");

  //Fill the combo:
  m_Combo.append("something");
  m_Combo.append("something else");
  m_Combo.append("something or other");
  m_Combo.set_active(0);

  add(m_Combo);

  //Connect signal handlers:
  m_Combo.signal_changed().connect(sigc::mem_fun(*this,
    &ExampleWindow::on_combo_changed) );

  auto entry = m_Combo.get_entry();
  if (entry)
  {
    entry->signal_changed().connect(sigc::mem_fun(*this,
      &ExampleWindow::on_entry_changed));
    m_ConnectionHasFocusChanged = entry->property_has_focus().signal_changed().
      connect(sigc::mem_fun(*this, &ExampleWindow::on_entry_has_focus_changed));
  }
  else
    std::cout << "No Entry ???" << std::endl;

  m_Combo.property_has_frame() = false;
}

ExampleWindow::~ExampleWindow()
{
  // The has_focus changed signal may be emitted while m_Combo is being destructed.
  // The signal handler can generate critical messages, if it's called when
  // m_Combo has been partly destructed.
  m_ConnectionHasFocusChanged.disconnect();
}

void ExampleWindow::on_combo_changed()
{
  std::cout << "on_combo_changed(): Row=" << m_Combo.get_active_row_number()
    << ", Text=" << m_Combo.get_active_text() << std::endl;
}

void ExampleWindow::on_entry_changed()
{
  std::cout << "on_entry_changed(): Row=" << m_Combo.get_active_row_number()
    << ", Text=" << m_Combo.get_active_text() << std::endl;
}

void ExampleWindow::on_entry_has_focus_changed()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    const bool entry_has_focus = entry->has_focus();
    if (m_entry_had_focus && !entry_has_focus)
    {
      // entry->has_focus() has changed from true to false; entry has lost focus.
      std::cout << "on_entry_has_focus_changed() to not focused: Row="
        << m_Combo.get_active_row_number() << ", ID=" << entry->get_text() << std::endl;
    }
    m_entry_had_focus = entry_has_focus;
  }
}